Increasingly, in an effort to reduce aircraft weight, designers are turning to the use of composite ply assemblies for the manufacture of structural and skin assemblies. Composite application systems and methods incorporating this fiber placement approach have been developed as described in U.S. Pat. No. 4,699,683. This type of composite line assembly structure and method involves the alignment of plural strips in contiguous edge contact so as to form a single wide band of composite ply strips. The ply strips can vary in width depending on the contour or tracking capability required for the specific structural application. A typical band is formed of 12 individual ¼ inch wide ply, or tape, strips for a total output bandwidth of 3 inches. Thus, a plurality of 3 inch bands would be placed in contiguous edge contact at predetermined orientation until the structure tooling mold is coated. A further embodiment of this type of fiber placement apparatus provides the capability to add, drop off or cut any or all of the contiguous strips allowing tailored flexibility in the configuration and orientation of the individual ply strips in the manufactured ply assembly.
Fiber lamentation cutting methods have suffered from a lack of operational capability to alter the orientation of the shear cut angle of each constituent tape from a fixed perpendicular cut as referenced to the centerline direction of the applied ply strip. As a result, ply cuts, or drop offs, occurring during predetermined path applications of +/−45° produce triangular patterns known as crenelations. The resolution of the resulting step triangulation is related both to the composite tape strip width and the applied orientation, or angle. Each constituent ply strip within the total bandwidth of strips incorporates this triangular pattern, or crenelation, with each cut. As a result, at the completion of the tape cutting sequence, the thus-produced edge of the composite ply assembly includes a triangular pattern.
Engineered composite assemblies typically include numerous ply laminations each formed by means of an orientation tailored segmented tape cutting process. The very large number of accumulated small tape triangular patterns or crenelations, formed in the built-up laminated ply assembly result in additional structural weight without the benefits of increased structural integrity and mechanical strength.
The embodiments of the disclosure are intended to overcome the limitations of the prior art by providing improved apparatus and method for the automated manufacture of composite structural assemblies which include precisely defined, linear edges formed at virtually any angle relative to the longitudinal axes of the connected ply strips and which do not include triangular patterns, or crenelations.